The veritcal rails come off and mount to the tv. There are several holes up and down to mount a variety of tvs the have different mounting patterns. The tv with vertical rails on the back then mount and secure to the horizontal piece.
I have the bolt hardware I used for my phillips TV. I don’t have the other misc. bolts that came with it for other tvs. The stand its self orginally only came with a couple sizes. But they are common size bolts that can be found at any hardware store or lowes for less then a dollar